CALGARY - A man who has been under investigation in the disappearance of a Calgary boy and his grandparents has been formally charged with their murders.

Calgary police said today that Douglas Garland, 54, was charged with first-degree murder in the deaths of Alvin and Kathryn Liknes, and second-degree murder in the death of five-year-old Nathan O'Brien.

With his hands handcuffed behind his back, Garland walked with his head down and showed little emotion as he was surrounded by cameras and reporters during the walk to the police department's arrest processing unit late Monday night.

He did not respond to a barrage of questions.

Calgary police Chief Rick Hanson said an arrest had been made earlier in the day Monday but said the person couldn't be identified until the charges were made official.

Garland lives on an acreage near Airdrie, just north of Calgary, where much of the search by police has been concentrated since the trio vanished from the Likness home on June 29.

The couple had held an estate sale at their home that weekend and their grandon stayed for a sleepover, but when his mother came to get him the next morning, no one was home.

So far, no bodies have been found.

Garland's next court appearance is scheduled for Wednesday.